System and Method for Accelerated I/O Access Using Storage Array Driver in Off-The-Shelf Server

ABSTRACT

A method, computer program product, and computer system for receiving, by a computing device, an I/O request. It may be identified whether the I/O request is eligible for handling via a first path without also requiring handling via a second path. If the I/O request is eligible, the I/O request may be processed via the first path on a host I/O stack without processing the I/O request via the second path on a storage array I/O stack. If the I/O request is ineligible, the I/O request may be processed via the first path on the host

CROSS-REFERENCE TO RELATED APPLICATIONS

The subject application is a continuation of U.S. application Ser. No.No. 15/799,571; filed Oct. 31, 2017. The entire disclosure of which isherein incorporated by reference.

BACKGROUND

Generally, with the increasing amounts of information being stored, itmay be beneficial to efficiently store and manage that information.While there may be numerous techniques for storing and managinginformation, each technique may have tradeoffs between reliability andefficiency.

BRIEF SUMMARY OF DISCLOSURE

In one example implementation, a method, performed by one or morecomputing devices, may include but is not limited to receiving, by acomputing device, an I/O request. It may be identified whether the I/Orequest is eligible for handling via a first path without also requiringhandling via a second path. If the I/O request is eligible, the I/Orequest may be processed via the first path on a host I/O stack withoutprocessing the I/O request via the second path on a storage array I/Ostack. If the I/O request is ineligible, the I/O request may beprocessed via the first path on the host I/O stack and via the secondpath on the storage array I/O stack.

One or more of the following example features may be included. Aneligible I/O request may include one of a data read request and a datawrite request. An ineligible I/O request may include at least one of acontrol command and an I/O request satisfying a predetermined condition.Processing the I/O request via the first path on the host I/O stackwithout processing the I/O request via the second path on the storagearray I/O stack may include processing an optimistic query. Processingthe I/O request via the first path on the host I/O stack withoutprocessing the I/O request via the second path on the storage array I/Ostack may include generating a metadata query based upon, at least inpart, the I/O request. The I/O request may be processed via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack when processing of the I/O request via the host I/O stack onthe first path without processing the I/O request via the second path onthe storage array I/O stack fails. A completion status may be returnedto an application layer of the host I/O stack when processing of the I/Orequest via the host I/O stack on the first path without processing theI/O request via the second path on the storage array I/O stacksuccessfully completes.

In another example implementation, a computing system may include one ormore processors and one or more memories configured to performoperations that may include but are not limited to receiving an I/Orequest. It may be identified whether the I/O request is eligible forhandling via a first path without also requiring handling via a secondpath. If the I/O request is eligible, the I/O request may be processedvia the first path on a host I/O stack without processing the I/Orequest via the second path on a storage array I/O stack. If the I/Orequest is ineligible, the I/O request may be processed via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack.

One or more of the following example features may be included. Aneligible I/O request may include one of a data read request and a datawrite request. An ineligible I/O request may include at least one of acontrol command and an I/O request satisfying a predetermined condition.Processing the I/O request via the first path on the host I/O stackwithout processing the I/O request via the second path on the storagearray I/O stack may include processing an optimistic query. Processingthe I/O request via the first path on the host I/O stack withoutprocessing the I/O request via the second path on the storage array I/Ostack may include generating a metadata query based upon, at least inpart, the I/O request. The I/O request may be processed via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack when processing of the I/O request via the host I/O stack onthe first path without processing the I/O request via the second path onthe storage array I/O stack fails. A completion status may be returnedto an application layer of the host I/O stack when processing of the I/Orequest via the host I/O stack on the first path without processing theI/O request via the second path on the storage array I/O stacksuccessfully completes.

In another example implementation, a computer program product may resideon a computer readable storage medium having a plurality of instructionsstored thereon which, when executed across one or more processors, maycause at least a portion of the one or more processors to performoperations that may include but are not limited to receiving an I/Orequest. It may be identified whether the I/O request is eligible forhandling via a first path without also requiring handling via a secondpath. If the I/O request is eligible, the I/O request may be processedvia the first path on a host I/O stack without processing the I/Orequest via the second path on a storage array I/O stack. If the I/Orequest is ineligible, the I/O request may be processed via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack.

One or more of the following example features may be included. Aneligible I/O request may include one of a data read request and a datawrite request. An ineligible I/O request may include at least one of acontrol command and an I/O request satisfying a predetermined condition.Processing the I/O request via the first path on the host I/O stackwithout processing the I/O request via the second path on the storagearray I/O stack may include processing an optimistic query. Processingthe I/O request via the first path on the host I/O stack withoutprocessing the I/O request via the second path on the storage array I/Ostack may include generating a metadata query based upon, at least inpart, the I/O request. The I/O request may be processed via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack when processing of the I/O request via the host I/O stack onthe first path without processing the I/O request via the second path onthe storage array I/O stack fails. A completion status may be returnedto an application layer of the host I/O stack when processing of the I/Orequest via the host I/O stack on the first path without processing theI/O request via the second path on the storage array I/O stacksuccessfully completes.

The details of one or more example implementations are set forth in theaccompanying drawings and the description below. Other possible examplefeatures and/or possible example advantages will become apparent fromthe description, the drawings, and the claims. Some implementations maynot have those possible example features and/or possible exampleadvantages, and such possible example features and/or possible exampleadvantages may not necessarily be required of some implementations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example diagrammatic view of an Off-the-shelf (OTS) processcoupled to an example distributed computing network according to one ormore example implementations of the disclosure;

FIG. 2 is an example diagrammatic view of a computer of FIG. 1 accordingto one or more example implementations of the disclosure;

FIG. 3 is an example diagrammatic view of a storage target of FIG. 1according to one or more example implementations of the disclosure;

FIG. 4 is an example diagrammatic view of an example SAN Model accordingto one or more example implementations of the disclosure;

FIG. 5 is an example diagrammatic view of an example SAN Model accordingto one or more example implementations of the disclosure;

FIG. 6 is an example flowchart of a OTS process according to one or moreexample implementations of the disclosure;

FIG. 7 is an example diagrammatic view of an example off-the-shelf modelaccording to one or more example implementations of the disclosure;

FIG. 8 is an example diagrammatic view of an example off-the-shelf modelaccording to one or more example implementations of the disclosure; and

FIG. 9 is an example diagrammatic view of an example storage systemlayout according to one or more example implementations of thedisclosure.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION System Overview

In some implementations, the present disclosure may be embodied as amethod, system, or computer program product. Accordingly, in someimplementations, the present disclosure may take the form of an entirelyhardware implementation, an entirely software implementation (includingfirmware, resident software, micro-code, etc.) or an implementationcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore, insome implementations, the present disclosure may take the form of acomputer program product on a computer-usable storage medium havingcomputer-usable program code embodied in the medium.

In some implementations, any suitable computer usable or computerreadable medium (or media) may be utilized. The computer readable mediummay be a computer readable signal medium or a computer readable storagemedium. The computer-usable, or computer-readable, storage medium(including a storage device associated with a computing device or clientelectronic device) may be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or any suitable combination ofthe foregoing. More specific examples (a non-exhaustive list) of thecomputer-readable medium may include the following: an electricalconnection having one or more wires, a portable computer diskette, ahard disk, a random access memory (RAM), a read-only memory (ROM), anerasable programmable read-only memory (EPROM or Flash memory), anoptical fiber, a portable compact disc read-only memory (CD-ROM), anoptical storage device, a digital versatile disk (DVD), a static randomaccess memory (SRAM), a memory stick, a floppy disk, a mechanicallyencoded device such as punch-cards or raised structures in a groovehaving instructions recorded thereon, a media such as those supportingthe internet or an intranet, or a magnetic storage device. Note that thecomputer-usable or computer-readable medium could even be a suitablemedium upon which the program is stored, scanned, compiled, interpreted,or otherwise processed in a suitable manner, if necessary, and thenstored in a computer memory. In the context of the present disclosure, acomputer-usable or computer-readable, storage medium may be any tangiblemedium that can contain or store a program for use by or in connectionwith the instruction execution system, apparatus, or device.

In some implementations, a computer readable signal medium may include apropagated data signal with computer readable program code embodiedtherein, for example, in baseband or as part of a carrier wave. In someimplementations, such a propagated signal may take any of a variety offorms, including, but not limited to, electro-magnetic, optical, or anysuitable combination thereof. In some implementations, the computerreadable program code may be transmitted using any appropriate medium,including but not limited to the internet, wireline, optical fibercable, RF, etc. In some implementations, a computer readable signalmedium may be any computer readable medium that is not a computerreadable storage medium and that can communicate, propagate, ortransport a program for use by or in connection with an instructionexecution system, apparatus, or device.

In some implementations, computer program code for carrying outoperations of the present disclosure may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java®, Smalltalk, C++ or the like.Java® and all Java-based trademarks and logos are trademarks orregistered trademarks of Oracle and/or its affiliates. However, thecomputer program code for carrying out operations of the presentdisclosure may also be written in conventional procedural programminglanguages, such as the “C” programming language, PASCAL, or similarprogramming languages, as well as in scripting languages such asJavascript, PERL, or Python. The program code may execute entirely onthe user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough a local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theinternet using an Internet Service Provider). In some implementations,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGAs) or other hardwareaccelerators, micro-controller units (MCUs), or programmable logicarrays (PLAs) may execute the computer readable programinstructions/code by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present disclosure.

In some implementations, the flowchart and block diagrams in the figuresillustrate the architecture, functionality, and operation of possibleimplementations of apparatus (systems), methods and computer programproducts according to various implementations of the present disclosure.Each block in the flowchart and/or block diagrams, and combinations ofblocks in the flowchart and/or block diagrams, may represent a module,segment, or portion of code, which comprises one or more executablecomputer program instructions for implementing the specified logicalfunction(s)/act(s). These computer program instructions may be providedto a processor of a general purpose computer, special purpose computer,or other programmable data processing apparatus to produce a machine,such that the computer program instructions, which may execute via theprocessor of the computer or other programmable data processingapparatus, create the ability to implement one or more of thefunctions/acts specified in the flowchart and/or block diagram block orblocks or combinations thereof. It should be noted that, in someimplementations, the functions noted in the block(s) may occur out ofthe order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved.

In some implementations, these computer program instructions may also bestored in a computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks or combinations thereof.

In some implementations, the computer program instructions may also beloaded onto a computer or other programmable data processing apparatusto cause a series of operational steps to be performed (not necessarilyin a particular order) on the computer or other programmable apparatusto produce a computer implemented process such that the instructionswhich execute on the computer or other programmable apparatus providesteps for implementing the functions/acts (not necessarily in aparticular order) specified in the flowchart and/or block diagram blockor blocks or combinations thereof.

Referring now to the example implementation of FIG. 1, there is shownoff-the-shelf (OTS) process 10 that may reside on and may be executed bya computer (e.g., computer 12), which may be connected to a network(e.g., network 14) (e.g., the internet or a local area network).Examples of computer 12 (and/or one or more of the client electronicdevices noted below) may include, but are not limited to, a storagesystem (e.g., a Network Attached Storage (NAS) system, a Storage AreaNetwork (SAN)), a personal computer(s), a laptop computer(s), mobilecomputing device(s), a server computer, a series of server computers, amainframe computer(s), or a computing cloud(s). As is known in the art,a SAN may include one or more of the client electronic devices,including a RAID device and a NAS system. In some implementations, eachof the aforementioned may be generally described as a computing device.In certain implementations, a computing device may be a physical orvirtual device. In many implementations, a computing device may be anydevice capable of performing operations, such as a dedicated processor,a portion of a processor, a virtual processor, a portion of a virtualprocessor, portion of a virtual device, or a virtual device. In someimplementations, a processor may be a physical processor or a virtualprocessor. In some implementations, a virtual processor may correspondto one or more parts of one or more physical processors. In someimplementations, the instructions/logic may be distributed and executedacross one or more processors, virtual or physical, to execute theinstructions/logic. Computer 12 may execute an operating system, forexample, but not limited to, Microsoft® Windows®; Mac® OS X®; Red Hat®Linux®, Windows® Mobile, Chrome OS, Blackberry OS, Fire OS, or a customoperating system. (Microsoft and Windows are registered trademarks ofMicrosoft Corporation in the United States, other countries or both; Macand OS X are registered trademarks of Apple Inc. in the United States,other countries or both; Red Hat is a registered trademark of Red HatCorporation in the United States, other countries or both; and Linux isa registered trademark of Linus Torvalds in the United States, othercountries or both).

In some implementations, as will be discussed below in greater detail, aOTS process, such as OTS process 10 of FIG. 1, may receive, by acomputing device, an I/O request (e.g., I/O 15). It may be identifiedwhether the I/O request is eligible for handling via a first pathwithout also requiring handling via a second path. If the I/O request iseligible, the I/O request may be processed via the first path on a hostI/O stack without processing the I/O request via the second path on astorage array I/O stack. If the I/O request is ineligible, the I/Orequest may be processed via the first path on the host I/O stack andvia the second path on the storage array I/O stack.

In some implementations, the instruction sets and subroutines of OTSprocess 10, which may be stored on storage device, such as storagedevice 16, coupled to computer 12, may be executed by one or moreprocessors and one or more memory architectures included within computer12. In some implementations, storage device 16 may include but is notlimited to: a hard disk drive; all forms of flash memory storagedevices; a tape drive; an optical drive; a RAID array (or other array);a random access memory (RAM); a read-only memory (ROM); or combinationthereof. In some implementations, storage device 16 may be organized asan extent, an extent pool, a RAID extent (e.g., an example 4D+1P R5,where the RAID extent may include, e.g., five storage device extentsthat may be allocated from, e.g., five different storage devices), amapped RAID (e.g., a collection of RAID extents), or combinationthereof.

In some implementations, network 14 may be connected to one or moresecondary networks (e.g., network 18), examples of which may include butare not limited to: a local area network; a wide area network; or anintranet, for example.

In some implementations, computer 12 may include a data store, such as adatabase (e.g., relational database, object-oriented database,triplestore database, etc.) and may be located within any suitablememory location, such as storage device 16 coupled to computer 12. Insome implementations, data, metadata, information, etc. describedthroughout the present disclosure may be stored in the data store. Insome implementations, computer 12 may utilize any known databasemanagement system such as, but not limited to, DB2, in order to providemulti-user access to one or more databases, such as the above notedrelational database. In some implementations, the data store may also bea custom database, such as, for example, a flat file database or an XMLdatabase. In some implementations, any other form(s) of a data storagestructure and/or organization may also be used. In some implementations,OTS process 10 may be a component of the data store, a standaloneapplication that interfaces with the above noted data store and/or anapplet/application that is accessed via client applications 22, 24, 26,28. In some implementations, the above noted data store may be, in wholeor in part, distributed in a cloud computing topology. In this way,computer 12 and storage device 16 may refer to multiple devices, whichmay also be distributed throughout the network. An example cloudcomputing environment that may be used with the disclosure may includebut is not limited to, e.g., Elastic Cloud Storage™ from Dell EMC™ ofHopkinton, Mass. In some implementations, other cloud computingenvironments may be used without departing from the scope of thedisclosure.

In some implementations, computer 12 may execute a storage managementapplication (e.g., storage management application 21), examples of whichmay include, but are not limited to, e.g., a storage system application,a cloud computing application, a data synchronization application, adata migration application, a garbage collection application, or otherapplication that allows for the implementation and/or management of datain a clustered (or non-clustered) environment (or the like). In someimplementations, OTS process 10 and/or storage management application 21may be accessed via one or more of client applications 22, 24, 26, 28.In some implementations, OTS process 10 may be a standalone application,or may be an applet/application/script/extension that may interact withand/or be executed within storage management application 21, a componentof storage management application 21, and/or one or more of clientapplications 22, 24, 26, 28. In some implementations, storage managementapplication 21 may be a standalone application, or may be anapplet/application/script/extension that may interact with and/or beexecuted within OTS process 10, a component of OTS process 10, and/orone or more of client applications 22, 24, 26, 28. In someimplementations, one or more of client applications 22, 24, 26, 28 maybe a standalone application, or may be anapplet/application/script/extension that may interact with and/or beexecuted within and/or be a component of OTS process 10 and/or storagemanagement application 21. Examples of client applications 22, 24, 26,28 may include, but are not limited to, e.g., a storage systemapplication, a cloud computing application, a data synchronizationapplication, a data migration application, a garbage collectionapplication, or other application that allows for the implementationand/or management of data in a clustered (or non-clustered) environment(or the like), a standard and/or mobile web browser, an emailapplication (e.g., an email client application), a textual and/or agraphical user interface, a customized web browser, a plugin, anApplication Programming Interface (API), or a custom application. Theinstruction sets and subroutines of client applications 22, 24, 26, 28,which may be stored on storage devices 30, 32, 34, 36, coupled to clientelectronic devices 38, 40, 42, 44, may be executed by one or moreprocessors and one or more memory architectures incorporated into clientelectronic devices 38, 40, 42, 44.

In some implementations, one or more of storage devices 30, 32, 34, 36,may include but are not limited to: hard disk drives; flash drives, tapedrives; optical drives; RAID arrays; random access memories (RAM); andread-only memories (ROM). Examples of client electronic devices 38, 40,42, 44 (and/or computer 12) may include, but are not limited to, apersonal computer (e.g., client electronic device 38), a laptop computer(e.g., client electronic device 40), a smart/data-enabled, cellularphone (e.g., client electronic device 42), a notebook computer (e.g.,client electronic device 44), a tablet, a server, a television, a smarttelevision, a media (e.g., video, photo, etc.) capturing device, and adedicated network device. Client electronic devices 38, 40, 42, 44 mayeach execute an operating system, examples of which may include but arenot limited to, Android™, Apple® iOS®, Mac® OS X®; Red Hat® Linux®,Windows® Mobile, Chrome OS, Blackberry OS, Fire OS, or a customoperating system.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality ofOTS process 10 (and vice versa). Accordingly, in some implementations,OTS process 10 may be a purely server-side application, a purelyclient-side application, or a hybrid server-side/client-side applicationthat is cooperatively executed by one or more of client applications 22,24, 26, 28 and/or OTS process 10.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality ofstorage management application 21 (and vice versa). Accordingly, in someimplementations, storage management application 21 may be a purelyserver-side application, a purely client-side application, or a hybridserver-side/client-side application that is cooperatively executed byone or more of client applications 22, 24, 26, 28 and/or storagemanagement application 21. As one or more of client applications 22, 24,26, 28, OTS process 10, and storage management application 21, takensingly or in any combination, may effectuate some or all of the samefunctionality, any description of effectuating such functionality viaone or more of client applications 22, 24, 26, 28, OTS process 10,storage management application 21, or combination thereof, and anydescribed interaction(s) between one or more of client applications 22,24, 26, 28, OTS process 10, storage management application 21, orcombination thereof to effectuate such functionality, should be taken asan example only and not to limit the scope of the disclosure.

In some implementations, one or more of users 46, 48, 50, 52 may accesscomputer 12 and OTS process 10 (e.g., using one or more of clientelectronic devices 38, 40, 42, 44) directly through network 14 orthrough secondary network 18. Further, computer 12 may be connected tonetwork 14 through secondary network 18, as illustrated with phantomlink line 54. OTS process 10 may include one or more user interfaces,such as browsers and textual or graphical user interfaces, through whichusers 46, 48, 50, 52 may access OTS process 10.

In some implementations, the various client electronic devices may bedirectly or indirectly coupled to network 14 (or network 18). Forexample, client electronic device 38 is shown directly coupled tonetwork 14 via a hardwired network connection. Further, clientelectronic device 44 is shown directly coupled to network 18 via ahardwired network connection. Client electronic device 40 is shownwirelessly coupled to network 14 via wireless communication channel 56established between client electronic device 40 and wireless accesspoint (i.e., WAP) 58, which is shown directly coupled to network 14. WAP58 may be, for example, an IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, Wi-Fi®, RFID, and/or Bluetooth™ (including Bluetooth™ LowEnergy) device that is capable of establishing wireless communicationchannel 56 between client electronic device 40 and WAP 58. Clientelectronic device 42 is shown wirelessly coupled to network 14 viawireless communication channel 60 established between client electronicdevice 42 and cellular network/bridge 62, which is shown by exampledirectly coupled to network 14.

In some implementations, some or all of the IEEE 802.11x specificationsmay use Ethernet protocol and carrier sense multiple access withcollision avoidance (i.e., CSMA/CA) for path sharing. The various802.11x specifications may use phase-shift keying (i.e., PSK) modulationor complementary code keying (i.e., CCK) modulation, for example.Bluetooth™ (including Bluetooth™ Low Energy) is a telecommunicationsindustry specification that allows, e.g., mobile phones, computers,smart phones, and other electronic devices to be interconnected using ashort-range wireless connection. Other forms of interconnection (e.g.,Near Field Communication (NFC)) may also be used.

In some implementations, various I/O requests (e.g., I/O request 15) maybe sent from, e.g., client applications 22, 24, 26, 28 to, e.g.,computer 12. Examples of I/O request 15 may include but are not limitedto, data write requests (e.g., a request that content be written tocomputer 12) and data read requests (e.g., a request that content beread from computer 12).

Data Storage System

Referring also to the example implementation of FIGS. 2-3 (e.g., wherecomputer 12 may be configured as a data storage system), computer 12 mayinclude storage processor 100 (which may instead be a general purposeprocessor) and a plurality of storage targets (e.g., storage targets102, 104, 106, 108, 110). In some implementations, storage targets 102,104, 106, 108, 110 may include any of the above-noted storage devices.In some implementations, storage targets 102, 104, 106, 108, 110 may beconfigured to provide various levels of performance and/or highavailability. For example, storage targets 102, 104, 106, 108, 110 maybe configured to form a non-fully-duplicative fault-tolerant datastorage system (such as a non-fully-duplicative RAID data storagesystem), examples of which may include but are not limited to: RAID 3arrays, RAID 4 arrays, RAID 5 arrays, and/or RAID 6 arrays. It will beappreciated that various other types of RAID arrays may be used withoutdeparting from the scope of the present disclosure.

While in this particular example, computer 12 is shown to include fivestorage targets (e.g., storage targets 102, 104, 106, 108, 110), this isfor example purposes only and is not intended limit the presentdisclosure. For instance, the actual number of storage targets may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

Further, the storage targets (e.g., storage targets 102, 104, 106, 108,110) included with computer 12 may be configured to form a plurality ofdiscrete storage arrays. For instance, and assuming for example purposesonly that computer 12 includes, e.g., ten discrete storage targets, afirst five targets (of the ten storage targets) may be configured toform a first RAID array and a second five targets (of the ten storagetargets) may be configured to form a second RAID array.

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may be configured to store coded data (e.g., via storagemanagement application 21), wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage targets102, 104, 106, 108, 110. Examples of such coded data may include but isnot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage targets 102, 104, 106, 108, 110 or maybe stored within a specific storage target.

Examples of storage targets 102, 104, 106, 108, 110 may include one ormore data arrays, wherein a combination of storage targets 102, 104,106, 108, 110 (and any processing/control systems associated withstorage management application 21) may form data array 112.

The manner in which computer 12 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, computer 12 may be configured as a SAN (i.e., a Storage AreaNetwork), in which storage processor 100 may be, e.g., a dedicatedcomputing system and each of storage targets 102, 104, 106, 108, 110 maybe a RAID device.

In the example where computer 12 is configured as a SAN, the variouscomponents of computer 12 (e.g., storage processor 100, and storagetargets 102, 104, 106, 108, 110) may be coupled using networkinfrastructure 114, examples of which may include but are not limited toan Ethernet (e.g., Layer 2 or Layer 3) network, a fiber channel network,an InfiniBand network, or any other circuit switched/packet switchednetwork.

As discussed above, various I/O requests (e.g., I/O request 15) may begenerated. For example, these I/O requests may be sent from, e.g.,client applications 22, 24, 26, 28 to, e.g., computer 12.Additionally/alternatively, I/O requests may be generated by computer12, where the generated I/Os may be due to processing requests from,e.g., client applications 22, 24, 26, 28. Additionally/alternatively(e.g., when storage processor 100 is configured as an application serveror otherwise), these I/O requests may be internally generated withinstorage processor 100 (e.g., via a server application, such as serverapplication 23). Examples of I/O request 15 may include but are notlimited to data write request 116 (e.g., a request that content 118 bewritten to computer 12) and data read request 120 (e.g., a request thatcontent 118 be read from computer 12).

In some implementations, during operation of storage processor 100,content 118 to be written to computer 12 may be received and/orprocessed by storage processor 100 (e.g., via storage managementapplication 21). Additionally/alternatively (e.g., when storageprocessor 100 is configured as an application server or otherwise),content 118 to be written to computer 12 may be internally generated bystorage processor 100 (e.g., via server application 23).

As discussed above, the instruction sets and subroutines of storagemanagement application 21, which may be stored on storage device 16included within computer 12, may be executed by one or more processorsand one or more memory architectures included with computer 12.Accordingly, in addition to being executed on storage processor 100,some or all of the instruction sets and subroutines of storagemanagement application 21 (and/or OTS process 10) may be executed by oneor more processors and one or more memory architectures included withdata array 112.

In some implementations, storage processor 100 may include front endcache memory system 122 (e.g., host-based cache memory). Examples offront end cache memory system 122 may include but are not limited to avolatile, solid-state, cache memory system (e.g., a dynamic RAM cachememory system), a non-volatile, solid-state, cache memory system (e.g.,a flash-based, cache memory system), and/or any of the above-notedstorage devices.

In some implementations, storage processor 100 may initially storecontent 118 within front end cache memory system 122. Depending upon themanner in which front end cache memory system 122 is configured, storageprocessor 100 (e.g., via storage management application 21) mayimmediately write content 118 to data array 112 (e.g., if front endcache memory system 122 is configured as a write-through cache) or maysubsequently write content 118 to data array 112 (e.g., if front endcache memory system 122 is configured as a write-back cache).

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may include a backend cache memory system. Examples of thebackend cache memory system (e.g., array-based cache memory) may includebut are not limited to a volatile, solid-state, cache memory system(e.g., a dynamic RAM cache memory system), a non-volatile, solid-state,cache memory system (e.g., a flash-based, cache memory system), and/orany of the above-noted storage devices.

Storage Targets

As discussed above, one or more of storage targets 102, 104, 106, 108,110 may be a RAID device. For instance, and referring also to FIG. 3,there is shown example target 150, wherein target 150 may be one exampleimplementation of a RAID implementation of, e.g., storage target 102,storage target 104, storage target 106, storage target 108, and/orstorage target 110. Examples of storage devices 154, 156, 158, 160, 162may include one or more electro-mechanical hard disk drives, one or moresolid-state/flash devices, and/or any of the above-noted storagedevices. It will be appreciated that while the term “disk” or “drive”may be used throughout, these may refer to and be used interchangeablywith any types of appropriate storage devices as the context andfunctionality of the storage device permits.

In some implementations, target 150 may include storage processor 152and a plurality of storage devices (e.g., storage devices 154, 156, 158,160, 162). Storage devices 154, 156, 158, 160, 162 may be configured toprovide various levels of performance and/or high availability (e.g.,via storage management application 21). For example, one or more ofstorage devices 154, 156, 158, 160, 162 (or any of the above-notedstorage devices) may be configured as a RAID 0 array, in which data isstriped across storage devices. By striping data across a plurality ofstorage devices, improved performance may be realized. However, RAID 0arrays may not provide a level of high availability. Accordingly, one ormore of storage devices 154, 156, 158, 160, 162 (or any of theabove-noted storage devices) may be configured as a RAID 1 array, inwhich data is mirrored between storage devices. By mirroring databetween storage devices, a level of high availability may be achieved asmultiple copies of the data may be stored within storage devices 154,156, 158, 160, 162.

While storage devices 154, 156, 158, 160, 162 are discussed above asbeing configured in a RAID 0 or RAID 1 array, this is for examplepurposes only and not intended to limit the present disclosure, as otherconfigurations are possible. For example, storage devices 154, 156, 158,160, 162 may be configured as a RAID 3, RAID 4, RAID 5 or RAID 6 array.

While in this particular example, target 150 is shown to include fivestorage devices (e.g., storage devices 154, 156, 158, 160, 162), this isfor example purposes only and not intended to limit the presentdisclosure. For instance, the actual number of storage devices may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

In some implementations, one or more of storage devices 154, 156, 158,160, 162 may be configured to store (e.g., via storage managementapplication 21) coded data, wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage devices154, 156, 158, 160, 162. Examples of such coded data may include but arenot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage devices 154, 156, 158, 160, 162 or maybe stored within a specific storage device.

The manner in which target 150 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, target 150 may be a RAID device in which storage processor 152is a RAID controller card and storage devices 154, 156, 158, 160, 162are individual “hot-swappable” hard disk drives. Another example oftarget 150 may be a RAID system, examples of which may include but arenot limited to an NAS (i.e., Network Attached Storage) device or a SAN(i.e., Storage Area Network).

In some implementations, storage target 150 may execute all or a portionof storage management application 21. The instruction sets andsubroutines of storage management application 21, which may be stored ona storage device (e.g., storage device 164) coupled to storage processor152, may be executed by one or more processors and one or more memoryarchitectures included with storage processor 152. Storage device 164may include but is not limited to any of the above-noted storagedevices.

As discussed above, computer 12 may be configured as a SAN, whereinstorage processor 100 may be a dedicated computing system and each ofstorage targets 102, 104, 106, 108, 110 may be a RAID device.Accordingly, when storage processor 100 processes data requests 116,120, storage processor 100 (e.g., via storage management application 21)may provide the appropriate requests/content (e.g., write request 166,content 168 and read request 170) to, e.g., storage target 150 (which isrepresentative of storage targets 102, 104, 106, 108 and/or 110).

In some implementations, during operation of storage processor 152,content 168 to be written to target 150 may be processed by storageprocessor 152 (e.g., via storage management application 21). Storageprocessor 152 may include cache memory system 172. Examples of cachememory system 172 may include but are not limited to a volatile,solid-state, cache memory system (e.g., a dynamic RAM cache memorysystem) and/or a non-volatile, solid-state, cache memory system (e.g., aflash-based, cache memory system). During operation of storage processor152, content 168 to be written to target 150 may be received by storageprocessor 152 (e.g., via storage management application 21) andinitially stored (e.g., via storage management application 21) withinfront end cache memory system 172.

Generally, a SAN Model may exist for a read I/O satisfied from a storagesystem data cache, such as but not limited to the VMAX™ data cacheoffered from Dell EMC™. For instance, and referring to the SAN ModelPart 1 in FIG. 4 and the SAN Model part 2 in FIG. 5, storage managementapplication 21 may receive an I/O in the application layer (1) on a hostserver, which may be funneled down through the block driver, protocoldriver (e.g., SCSI) and HBA driver (e.g., Fibre channel) to allow theread request to be sent via the SAN to a VMAX™ front end director (2).Generally, the left side of FIG. 4 may be the host or server (e.g.,computer 12). The right side may be the storage array software stack.The table in the middle may represent data and metadata structuresstored within the storage array, which generally do not live in theserver software stack. The I/O may be recognized on the VMAX™ side bythe HBA driver (3) and may then be routed through a few layers includinga protocol driver, VMAX™ device driver, and into the I/O subsystem. Atthis point, the I/O subsystem (e.g., via storage management application21) may perform a metadata subsystem query (4) (e.g., “Is this data incache?”). Metadata may be distributed on more than one server. Thismetadata subsystem query may result in a remote memory request on theserver IB network to one of the other servers to access the metadatacontent. After the server IB network internal request completes and theresults are returned to the I/O subsystem, another request may be madeof the cache subsystem to return the requested data (5). Cache data mayalso be distributed on more than one server. This cache subsystemrequest may result in a remote memory read request on the server IBnetwork to acquire the requested data and place it in memory that theHBA driver may then return to the host via a transfer over the SAN (6and 7). Once the data has been received by the HBA driver and the I/Ohas a successful logical completion received from the VMAX™ side, thedata may then be returned to the application layer (8).

While the above system may be beneficial for some implementations, forother implementations, it may be more beneficial and/or cheaper to use“off-the-shelf” or “general purpose” server CPUs for serving IOs intoand out of local storage devices. However, generally, software-definedstorage systems and hyper-converged infrastructure systems that may useoff-the-shelf server CPUs for serving IOs into and out of local storagedevices may have to re-implement all the data services at their level.Typically, users cannot leverage trusted data services from storagearrays in such SDS/HCI environments. To be clear, the above system mayalso use off-the-shelf servers, but they generally do not have aVMAX™-aware software component running in the off-shelf-server (e.g.,computer 12).

Thus, as will be discussed below, off-the-shelf (OTS) process 10 mayenable the taking of traditional storage array functionality, and movingpart or whole I/O processing into an off-the-shelf server CPU, whilemaintaining the storage array data services. In some implementations,this may be accomplished by having a VMAX™-aware software running incomputer 12, allowing it to be part of internal fabric 114. As will bediscussed below, OTS process 10 may at least help, e.g., the improvementof an existing storage technology, necessarily rooted in computertechnology in order to overcome an example and non-limiting problemspecifically arising in the realm of data storage. For instance, OTSprocess 10 may use an efficient process to take traditional storagearray functionality and move part or whole I/O processing into anoff-the-shelf server CPU, while maintaining the storage array dataservices.

The OTS Process

As discussed above and referring also at least to the exampleimplementations of FIGS. 6-9, OTS process 10 may receive 600, by acomputing device, an I/O request. OTS process 10 may identify 602whether the I/O request is eligible for handling via a first pathwithout also requiring handling via a second path. If the I/O request iseligible, OTS process 10 may process 604 the I/O request via the firstpath on a host I/O stack without processing the I/O request via thesecond path on a storage array I/O stack. If the I/O request isineligible, OTS process 10 may 606 the I/O request via the first path onthe host I/O stack and via the second path on the storage array I/Ostack.

In some implementations, OTS process 10 may receive 600, by a computingdevice, an I/O request. For instance, and referring at least to theexample implementation of FIGS. 7-8, an example, off-the-shelf (OTS)model (part 1) 700 and 800 (part 2) is shown. In the example, assume forexample purposes only that a user (e.g., user 46) would like to accessdata stored on the server metadata and data store. Such an I/O request(e.g., I/O 15) may be generated (e.g., via client computing device 38)and received 600 by OTS process 10. In some implementations, clientapplication 22 and user 46 may also be resident on computer 12, thus,the I/O request may also be generated by computer 12 (via OTS process10). In FIGS. 7 and 8, the left side may be the host or server (e.g.,computer 12). The right hand side may be the storage array softwarestack. The table in the middle may represent data and metadatastructures stored within the storage array, and generally do not live inthe server software stack.

In some implementations, OTS process 10 may identify 602 whether the I/Orequest is eligible for handling via a first path without also requiringhandling via a second path. For instance, in some implementations, I/O15 may be initiated (received) at the application layer and passedthrough the block device driver of the host I/O stack (of the OTS hostserver) to a point where I/O 15 may be identified 602 (e.g., recognized)as either being eligible for “fast path handling” (e.g., handling via afirst path, such as example steps (1)-(4) in FIGS. 7-8, without alsorequiring handling via a second path, such steps (3)-(7) in FIGS. 4-5).That is, the need to involve the second path on a storage array I/Ostack of the storage array server may be completely obviated, therebyenabling use of off-the-shelf or general purpose servers. Thus, in someimplementations, if the I/O request is eligible, OTS process 10 mayprocess 604 the I/O request via the first path on a host I/O stackwithout processing the I/O request via the second path on a storagearray I/O stack, and if the I/O request is ineligible, OTS process 10may 606 the I/O request via the first path on the host I/O stack and viathe second path on the storage array I/O stack.

In some implementations, the “fast path handling” shows how OTS process10 may process a host read command that is satisfied out of the storagearray cache. For instance, a quick metadata access by OTS process 10 mayhelp identify that the requested data is present in the storage arraycache and identify its location, where OTS process 10 may then fetch thedata from the storage array cache and place it into the host memory,providing the application layer with the requested data.

In some implementations, an eligible I/O request may include one of adata read request and a data write request, and an ineligible I/Orequest may include at least one of a control command and an I/O requestsatisfying a predetermined condition. For instance, in someimplementations, only data read and write requests may be identified 602as being eligible for fast path handling. Generally, control commandsmay be identified 602 as ineligible for fast path handling, and thuspotentially requiring “slow path handling,” such as the example shown inFIGS. 4-5. In some implementations, the Server Device Handling layer inthe host I/O stack may have awareness (e.g., through coordination withthe storage array) of whether there are any “special conditions” thatmay prevent fast path handling. For instance, if there is somecomplicated state that requires intimate, instantaneous knowledge ofwhat is happening in the storage array, rather than trying to keep thehost I/O stack fully up to date with all of the necessary information,OTS process 10 may determine it is easier for the host layer to pass thecommand on to the storage array for normal/legacy handling (i.e., “slowpath handling”).

In some implementations, the I/O request may be routed (e.g., calledfrom one layer into another layer) through abbreviated versions ofdevice and metadata subsystem handling by OTS process 10. For instance,there may be different layers of software functionality residing in thehost I/O stack. In some implementations, the host I/O stack changes mayprovide quick responses to I/O requests that cover the majority of casesand states. Thus, there may not be a need for the device and metadatasubsystem layers in the host I/O stack to deal with complicatedscenarios or system states. In some implementations, if OTS process 10identifies the presence of such a complicated state/scenario, or thatsome subtle handling may be needed, OTS process 10 may avoid using the“fast path handling” and may instead send I/O 15 to the storage arrayfor “normal” handling (e.g., “slow path handling”). Thus, an examplebenefit to be had in I/O response time may come from not loading thehost I/O stack with lots of complicated state handling, thereforeenabling OTS process 10 to make a quick go/no-go decision on the “fastpath handling” viability, and either proceed that way or offload the I/Oto the slow path handling route.

In some implementations, processing 604 the I/O request via the firstpath on the host I/O stack without processing the I/O request via thesecond path on the storage array I/O stack may include processing 608 anoptimistic query. For instance, the components in the host I/O stack maynot be sufficient to participate in “full management” of the metadatasubsystem (for example) like the storage system server; however, thosecomponents may have enough knowledge of that subsystem to satisfyoptimistic queries for “simple” (e.g., eligible) state handling. Asnoted above, anything too “complicated” (e.g., ineligible) may result inOTS process 10 passing I/O 15 to be processed 606 via the storage array.An example of less than “full management” of the metadata subsystem mayinclude, e.g., read-only access to metadata content.

Again, in the interest of being lightweight and fast, full metadatasubsystem access (including write/edit) capabilities may require heavy(i.e. costly) operations, such as array-level serialization semantics.If there are actions that the fast path logic of OTS process 10 mayundertake without needing to honor these semantics, while also havingthe ability to detect inconsistencies and silently retry if very smallrace conditions are hit, such actions may be attempted. For example, OTSprocess 10 may assume that the abbreviated metadata subsystem has a“good/optimistic” idea (but, not necessarily perfect or up-to-dateknowledge) of where to locate the metadata needed for I/O 15, and ifthis good (but, not perfect) view of things is incorrect, OTS process 10may have sufficient redundancy to recognize that fact and silently retryshould something have changed right around the time of the optimisticquery.

Generally, having “enough knowledge” may refer to the “good, but notnecessarily perfect,” view of the system. As an example, assume thatinside the storage array, any time it is desired to move (e.g., pageout, relocate, etc.) a piece of metadata, OTS process 10 may requirenotification and positive acknowledgement from all of the processorsinside the storage array. However, in the example host I/O stack model,OTS process 10 has a mechanism to learn this information lazily and thepicture of the system may be substantially correct (e.g., 99% correct,but likely not 100% correct).

In some implementations, and referring at least to the exampleimplementation of FIG. 9, an example storage system layout 900 with thestorage array Server Device Handling Layer is shown in more detail. TheServer Device Handling Layer (or the driver) brings storage arrayawareness to the server stack. In some implementations, processing 604the I/O request via the first path (e.g., where P1 is the first path andP2 is the second path in FIG. 9) on the host I/O stack withoutprocessing the I/O request via the second path on the storage array I/Ostack may include generating 610 a metadata query based upon, at leastin part, the I/O request. For instance, the metadata query (shown viastep (2)) may result in an internal fabric request and the result of thequery may be called back to the device handler layer. For example, thegenerated 610 metadata query may be built out of the storage arrayServer Device Handling Layer of the host I/O stack. I/O 15 may berequesting data from a particular range of the logical storage devicethat is presented to the application layer, and the metadata query maybe requesting the location/cache status of that data within the storagearray (e.g., “is this data in the array cache, and if so, what cacheaddress is it stored in?”), where the result may include, e.g., ano/yes+address answer.

In some implementations, after realizing that the desired data is in thecache, OTS process 10 (e.g., via the storage array Server DeviceHandling Layer) may generate a request called through an abbreviatedcache-awareness layer (similar to the metadata-aware layer, thiscomponent may satisfy optimistic queries but generally cannotparticipate in full cache management operations such as, e.g.,allocation, recycling, LRU updates, etc.) that may generate anotherfabric request to read the requested data from the cache, as shown instep (3). In some implementations, the request may include enoughinformation to describe how to transfer data from the storage arraycache into the host memory, and may include such information as, forexample, source and destination fabric addresses, information about howto ensure the self-consistency of the data (e.g., if the data has anexpected checksum, and if so what is that value, etc.). The fabricrequest may include, e.g., source and destination fabric addresses,self-consistency validation, etc.) and may be sent (via OTS process 10)to the fabric and messaging driver of the host I/O stack so that thefabric request may be turned into a physical request to read andvalidate some memory that resides in the storage array (e.g., the ServerMetadata and Data Store).

In some implementations, OTS process 10 may return 612 a completionstatus to an application layer of the host I/O stack when processing 604of the I/O request via the host I/O stack on the first path withoutprocessing the I/O request via the second path on the storage array I/Ostack successfully completes. For instance, upon the completion of thefabric operation, OTS process 10 may return 612 a completion status allthe way up to the application layer, as shown in step (4).

In some implementations, the I/O request may be processed 614 via thefirst path on the host I/O stack and via the second path on the storagearray I/O stack when processing 604 of the I/O request via the host I/Ostack on the first path without processing the I/O request via thesecond path on the storage array I/O stack fails. For instance, shouldthere be any sort of I/O failure in the fast path processing 604 (e.g.,processing 604 of the I/O request via the host I/O stack on the firstpath without processing the I/O request via the second path on thestorage array I/O stack) OTS process 10 may retry the processing of I/O15 by, e.g., using the slow path (e.g., processing 606 via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack).

Thus, in some implementations, OTS process 10 may bring awareness of thestorage array internal semantics into the host I/O stack server as a“driver” (e.g., the Server Device Handling Layer), e.g., in theoperating system. OTS process 10 may not have the full frontendfunctionality within the storage array; however, OTS process 10 mayencapsulate most of the I/O processing capabilities, such as where dataresides in the data persistence layers (e.g., in global memory or instorage media). In some implementations, OTS process 10 may enableoff-the-shelf computer elements to reside directly on the arraybackplane/fabric. This may enable low latency and high bandwidth accessto the data. In some implementations, OTS process 10 may includeenablement to cache the data (read only or read/write) locally on thepersistent media in servers (e.g., computer 12). This may extend arraylevel cache coherence and clustering capabilities to the servers, andmay help bring array based data closer to processing units (e.g.,CPU/GPU/TPU) in the servers for applications that may require highperformance/low latency operations, such as machine learning, artificialintelligence, OLTP and DSS/DWH RDMBs, no-sql DB s, etc.

The terminology used herein is for the purpose of describing particularimplementations only and is not intended to be limiting of thedisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. As used herein, the language “at least one of A, B,and C” (and the like) should be interpreted as covering only A, only B,only C, or any combination of the three, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps (notnecessarily in a particular order), operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps (not necessarily in a particular order),operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents (e.g., ofall means or step plus function elements) that may be in the claimsbelow are intended to include any structure, material, or act forperforming the function in combination with other claimed elements asspecifically claimed. The description of the present disclosure has beenpresented for purposes of illustration and description, but is notintended to be exhaustive or limited to the disclosure in the formdisclosed. Many modifications, variations, substitutions, and anycombinations thereof will be apparent to those of ordinary skill in theart without departing from the scope and spirit of the disclosure. Theimplementation(s) were chosen and described in order to explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various implementation(s) with various modifications and/or anycombinations of implementation(s) as are suited to the particular usecontemplated.

Having thus described the disclosure of the present application indetail and by reference to implementation(s) thereof, it will beapparent that modifications, variations, and any combinations ofimplementation(s) (including any modifications, variations,substitutions, and combinations thereof) are possible without departingfrom the scope of the disclosure defined in the appended claims.

What is claimed is:
 1. A computer-implemented method comprising:receiving, by a computing device, an I/O request; identifying a firstpath for processing I/O requests, wherein the first path includesprocessing by a general purpose processor; identifying a second path forprocessing I/O requests, wherein the second path includes processing bya special purpose storage processor; identifying whether the I/O requestis eligible for handling via a first path without also requiringhandling via a second path; if the I/O request is eligible, processingthe I/O request via the first path on a host I/O stack withoutprocessing the I/O request via the second path on a storage array I/Ostack; and if the I/O request is ineligible, processing the I/O requestvia the first path on the host I/O stack and via the second path on thestorage array I/O stack, wherein an ineligible I/O request includes atleast one of a control command and an I/O request satisfying apredetermined condition, wherein satisfying the predetermined conditionincludes a Server Device Handling layer in the host I/O stack configuredto determine, in coordination with the storage array I/O stack, whetherthe control command should be passed to the storage array I/O stack viathe second path.
 2. The computer-implemented method of claim 1 whereinan eligible I/O request includes one of a data read request and a datawrite request.
 3. The computer-implemented method of claim 1 furthercomprising processing the I/O request via the first path on the host I/Ostack and via the second path on the storage array I/O stack whenprocessing of the I/O request via the host I/O stack on the first pathwithout processing the I/O request via the second path on the storagearray I/O stack fails.
 4. The computer-implemented method of claim 1further comprising returning a completion status to an application layerof the host I/O stack when processing of the I/O request via the hostI/O stack on the first path without processing the I/O request via thesecond path on the storage array I/O stack successfully completes. 5.The computer-implemented method of claim 1 wherein the internal fabricrequest resulting from the metadata query includes requesting at leastone of a location status and a cache status of metadata within thestorage array I/O stack.
 6. A computer program product residing on anon-transitory computer readable storage medium having a plurality ofinstructions stored thereon which, when executed across one or moreprocessors, causes at least a portion of the one or more processors toperform operations comprising: receiving an I/O request; identifying afirst path for processing I/O requests, wherein the first path includesprocessing by a general purpose processor; identifying a second path forprocessing I/O requests, wherein the second path includes processing bya special purpose storage processor; identifying whether the I/O requestis eligible for handling via a first path without also requiringhandling via a second path; if the I/O request is eligible, processingthe I/O request via the first path on a host I/O stack withoutprocessing the I/O request via the second path on a storage array I/Ostack; and if the I/O request is ineligible, processing the I/O requestvia the first path on the host I/O stack and via the second path on thestorage array I/O stack, wherein an ineligible I/O request includes atleast one of a control command and an I/O request satisfying apredetermined condition, wherein satisfying the predetermined conditionincludes a Server Device Handling layer in the host I/O stack configuredto determine, in coordination with the storage array I/O stack, whetherthe control command should be passed to the storage array I/O stack viathe second path.
 7. The computer program product of claim 6 wherein aneligible I/O request includes one of a data read request and a datawrite request.
 8. The computer program product of claim 6 wherein theoperations further comprise processing the I/O request via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack when processing of the I/O request via the host I/O stack onthe first path without processing the I/O request via the second path onthe storage array I/O stack fails.
 9. The computer program product ofclaim 6 wherein the operations further comprise returning a completionstatus to an application layer of the host I/O stack when processing ofthe I/O request via the host I/O stack on the first path withoutprocessing the I/O request via the second path on the storage array I/Ostack successfully completes.
 10. The computer program product of claim6 wherein the internal fabric request resulting from the metadata queryincludes requesting at least one of a location status and a cache statusof metadata within the storage array I/O stack.
 11. A computing systemincluding one or more processors and one or more memories configured toperform operations comprising: receiving an I/O request; identifying afirst path for processing I/O requests, wherein the first path includesprocessing by a general purpose processor; identifying a second path forprocessing I/O requests, wherein the second path includes processing bya special purpose storage processor; identifying whether the I/O requestis eligible for handling via a first path without also requiringhandling via a second path; if the I/O request is eligible, processingthe I/O request via the first path on a host I/O stack withoutprocessing the I/O request via the second path on a storage array I/Ostack; and if the I/O request is ineligible, processing the I/O requestvia the first path on the host I/O stack and via the second path on thestorage array I/O stack, wherein an ineligible I/O request includes atleast one of a control command and an I/O request satisfying apredetermined condition, wherein satisfying the predetermined conditionincludes a Server Device Handling layer in the host I/O stack configuredto determine, in coordination with the storage array I/O stack, whetherthe control command should be passed to the storage array I/O stack viathe second path.
 12. The computing system of claim 11 wherein aneligible I/O request includes one of a data read request and a datawrite request.
 13. The computing system of claim 11 wherein theoperations further comprise processing the I/O request via the firstpath on the host I/O stack and via the second path on the storage arrayI/O stack when processing of the I/O request via the host I/O stack onthe first path without processing the I/O request via the second path onthe storage array I/O stack fails, and returning a completion status toan application layer of the host I/O stack when processing of the I/Orequest via the host I/O stack on the first path without processing theI/O request via the second path on the storage array I/O stacksuccessfully completes.
 14. The computing system of claim 11 wherein theinternal fabric request resulting from the metadata query includesrequesting at least one of a location status and a cache status ofmetadata within the storage array I/O stack.